Pesticides May Up Asthma in Farm Women

Dec. 28, 2007 -- Farm women who use pesticides are more likely than nonusers
to develop allergic asthma as adults, a U.S.
study shows.

This effect is particularly strong for the 60% of farm women who grew up on
a farm. People who grow up on farms have a reduced risk of allergies. Pesticide users have
less of this protection, find Jane A. Hoppin, ScD, of the National Institute of
Environmental Health Sciences, and colleagues.

"Growing up on a farm is such a huge protective effect it's pretty hard
to overwhelm it," Hoppin said in a news release. "There is a difference
in asthma prevalence between women
who did and did not use pesticides, but whether it is causal or not remains to
be seen."

Hoppin's team collected self-reported data from 25,814 farm women from Iowa
and North Carolina. This data included detailed information on pesticide use
and whether, as adults, they had doctor-diagnosed allergic or nonallergic
asthma.

Farm women who grew up on farms were about half as likely to have allergic
asthma (and about 20% less likely to have nonallergic asthma) as were women who
were not farm children. Yet pesticide use was most strongly linked to allergic
asthma in farm-raised women.

"It is likely that the association with pesticides is masked in the
general population due to a higher baseline rate of asthma," Hoppin
suggests.

Use of any pesticide on the farm upped a woman's risk of allergic asthma by
46%, but did not increase risk of nonallergic asthma. Even so, the risk was not
huge. Only 181 of 14,767 pesticide users reported allergic asthma.

Ten of 31 analyzed pesticides were linked to allergic asthma, including two
herbicides (2,4-D and glyphosate), seven insecticides (carbaryl, coumaphos,
DDT, malathion, parathion, permethrin on animals, and phorate), and one
fungicide (metalaxyl).

However, just because there is a link between pesticides and allergic asthma
doesn't necessarily mean pesticides cause asthma. Hoppin says that in 2008, her
team is hoping to start a new study to better evaluate this link.

Their current report appears in the Jan. 1 issue of the American Journal
of Respiratory and Critical Care.